Today, glass substrates and semiconductor substrates used in flat-screen display devices that employ liquid crystal or organic LEDs are widely subjected to processing in which ion implantation is performed using an ion implanter. Particularly, efficient and accurate ion implantation on a large-sized substrate requires a wide lateral width of the ion beam irradiated on the lateral width of the substrate and use of a ribbon ion beam in which the current density distribution is controlled to a desire distribution.
Using a ribbon ion beam having an ion beam lateral width that is wider than the substrate lateral width makes it possible to process the entire lateral width region of the substrate at once and, by moving the substrate in the vertical direction at this time, perform ion implantation on the entire substrate at once, thereby increasing processing efficiency.
On the other hand, a ribbon ion beam processes the same position of the substrate in the lateral width direction as in the vertical direction and thus when the current density distribution of this ribbon ion beam is not uniform in the lateral width direction, sections in which ion implantation was unevenly performed appear as lines on the substrate, resulting in failure to achieve accurate ion implantation. In consequence, it is desirable to accurately regulate the ribbon ion beam to a desired current density distribution.
In JP 2878112 B there is described an ion implanter that causes a multipolar magnetic field to act on a ribbon ion beam having a shape in which the cross-sectional shape of the ion beam has length and width dimensionality in the transverse direction, thereby suppressing the unevenness of the current density distribution of the ribbon ion beam.
Similarly, in JP 3730666 B there is described an ion implanter that, similar to JP 2878112 B, causes a multipolar magnetic field to act on the current density distribution of a ribbon ion beam, thereby regulating the current density distribution. The document states that, at this time, regulation of the current density distribution is performed based on the deviation between the ribbon ion beam distribution and the target distribution.
Furthermore, in JP 2005-327713 A there is described an ion implanter such as the following. That is, in the ion implanter, a sheet-shaped ion beam that includes a desired ion type and has a width wider than the width of the short side of the substrate is generated from an ion source, the sheet-shaped ion beam is then curved in a direction orthogonal to the sheet plane by a mass separation magnet, and the desired ion type is selectively extracted. At this time, a separation slit is used in coordination with the mass separation magnet to selectively permit the passing of the desired ion type. Subsequently, the substrate is moved back and forth in a direction substantially orthogonal to the sheet plane of the ion beam, within the irradiation range of the ion beam that has passed through the separation slit, to perform ion implantation.    PATENT DOCUMENT 1: JP 2878112 B    PATENT DOCUMENT 2: JP 3730666 B    PATENT DOCUMENT 3: JP 2005-327713 A